Gas turbine engines operate by passing a volume of gases through a series of compressors and turbines in order to produce rotational shaft power. High energy gases rotate a turbine to generate the shaft power. The shaft power drives a compressor to provide compressed air to a combustion process that generates the high energy gases for turning the turbine. In an aircraft engine, the turbine can be used to generate propulsion, such as directly via thrust, or indirectly via a shaft and fan or propeller. In an industrial gas turbine, the shaft power can drive a generator that produces electricity. Alternatively, a power turbine can be used to drive a shaft for powering the generator.
Each compressor and turbine includes a plurality of stages of stator vanes (also known as nozzles or stators) and rotor blades (also known as buckets), each vane and blade including an airfoil. In general, vanes redirect the trajectory of gases coming off the blades for flow into the next stage. In the compressor, vanes convert kinetic energy of moving gases into pressure, while, in the turbine, vanes accelerate pressurized gases to extract kinetic energy. In the compressor, the rotating blades push gases past the stationary vanes. In the turbine, the rotating blades extract rotational power from flowing gases.
In the compressor, the vanes are held in place along their base platforms by features of the compressor casing termed “hook fits”. Movement of gases against and across the vanes can cause some small movement of the vanes and their base platforms relative to the hook fits. Over time, this can wear the hook fits, necessitating a repair to achieve desired specifications and tolerances.
Several methods and apparatuses for repair of the hook fits have been utilized, including machining methods using handheld tools. However, such methods and apparatuses are subject to inefficiencies resulting from a lack of ergonomic design, a high degree of training required for personnel, a high degree of variability, cumbersomeness of the apparatuses utilized and a time-consuming setup process.